Because certain blood types are more likely to co-occur with varying levels of hormones in the body, physicians commonly tailor their exercise recommendations to the patient’s type. People with type A blood, for example, are more likely to have higher levels of cortisol, the stress hormone, in their body. So, stress-reducing exercises, like Tai Chi and yoga, may be more beneficial at cutting that tension than running or weightlifting alone.
When the adrenal gland dumps more and more cortisol into the blood, people’s stress response grows more acute. People with type A blood may find themselves getting anxious more quickly and having a harder time letting troubles roll off their back.
In a study of OCD sufferers done in 1983, Blood Type A was shown to be associated with a higher incidence of OCD over other types, in addition to a higher incidence of hysteria.